Cultural resources around all federal lands is protected. This includes ancient ruins, fossils, archaeological features and other such. Anyone found to be tampering with or destroying or stealing these resources will be fined and or arrested.
If you see it take a picture and leave it where it sits. The cultural resources need to be left alone so that others can enjoy them also.
Bring your camera and take home a memory and not a resource.
Here is the law that governs the protection of these resources.
Title 36, Code of Federal Regulations, section 327.14
Destruction, injury, defacement, removal or any alteration of public property including, but not limited to, developed facilities, natural formations, mineral deposits, historical and archaeological features, paleontological resources, boundary monuments or markers, and vegetative growth, is prohibited except when in accordance with written permission from the district engineer.